20、Web服务示例

如下是main.rs文件内容：

// src\main.rs
use hello::ThreadPool;
use std::thread;
use std::time::Duration;
use std::fs;
use std::io::prelude::*;
use std::net::TcpStream;
use std::net::TcpListener;

fn main() {
    let listener = TcpListener::bind("127.0.0.1:7878").unwrap();
    let pool = ThreadPool::new(4);

    for stream in listener.incoming().take(2) {
        let stream = stream.unwrap();

        pool.execute(|| {
            handle_connection(stream);
       });
    }

    println!("Shutting down")
}

fn handle_connection(mut stream: TcpStream) {
    let mut buffer = [0; 512];

    stream.read(&mut buffer).unwrap();

    let get = b"GET / HTTP/1.1\r\n";
    let sleep = b"GET /sleep HTTP/1.1\r\n";

    let (status_line, filename) = if buffer.starts_with(get) {
        ("HTTP/1.1 200 OK\r\n\r\n", "../hello.html")
    } else if buffer.starts_with(sleep) {
        thread::sleep(Duration::from_secs(5));
        ("HTTP/1.1 200 OK\r\n\r\n", "../hello.html")
    } else {
        ("HTTP/1.1 404 NOT FOUND\r\n\r\n", "../404.html")
    };

    let contents = fs::read_to_string(filename).unwrap();
    
    let response = format!("{}{}", status_line, contents);

    stream.write(response.as_bytes()).unwrap();
    stream.flush().unwrap();
}

如下是lib.rs内容：

//src/lib.rs
use std::sync::Arc;
use std::sync::Mutex;
use std::sync::mpsc;
use std::thread;


enum Message {
    NewJob(Job),
    Terminate,
}

pub struct ThreadPool {
    workers: Vec<Worker>,
    sender: mpsc::Sender<Message>,
}

type Job = Box<dyn FnOnce() + Send + 'static>;

impl ThreadPool {
    pub fn new(size: usize) -> ThreadPool {
        assert!(size > 0);
        
        let (sender, receiver) = mpsc::channel();

        let receiver = Arc::new(Mutex::new(receiver));

        let mut workers = Vec::with_capacity(size);

        for id in 0..size {
            workers.push(Worker::new(id, Arc::clone(&receiver)));
        }

        ThreadPool {
            workers,
            sender,
        }
    }

    pub fn execute<F>(&self, f: F)
        where
            F: FnOnce() + Send + 'static
                {
                    let job = Box::new(f);
                    self.sender.send(Message::NewJob(job)).unwrap();
                }
}


struct Worker {
    id: usize,
    thread: Option<thread::JoinHandle<()>>,
}

impl Worker {
    fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Message>>>) -> Worker {
        let thread = thread::spawn(move || {
           loop {
            let message = receiver.lock().unwrap().recv().unwrap();
            
            match message {
                Message::NewJob(job) => {
                    println!("Worker {} got a job; execting.", id);
                    job();
                },
                Message::Terminate => {
                    println!("Worker {} was told to terminate.", id);
                    break;
                },
            }
            }
        });

        Worker {
            id,
            thread: Some(thread),
        }
    }
}

impl Drop for ThreadPool {
    fn drop(&mut self) {
        println!("Sending terminate message to all workers.");

        for _ in &mut self.workers {
            self.sender.send(Message::Terminate).unwrap();
        }

        println!("Shutting down all workers.");

        for worker in &mut self.workers {
            println!("Shutting down worker {}", worker.id);
            
            if let Some(thread) = worker.thread.take() {
                thread.join().unwrap();
            }
        }
    }
}

如下是Cargo.toml内容：

//Cargo.toml
[package]
name = "l2015"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]

[lib]
name = "l2025"